This is a wonderful story. Staffers in the Sanders campaign, who are working on salary, complain that they are paid less than the $15 per hour that Senator Sanders advocates for the minimum wage. So Sanders raises their hourly wage. Does that increase their income? No, because he raised the hourly wage by cutting the number of hours they work!
Of course, if a President Sanders raised the federal minimum wage, I am sure he would be confident that the change would not have any adverse employment effects. Downward-sloping demand curves may describe socialist political campaigns, but back in the actual capitalist economy, the laws of supply and demand work completely differently.